stuffily

/ˈstʌfəli/
adverb
  1. In a way that is uncomfortably warm and lacking fresh air.
    • The old library smelled stuffily of dust and old paper.
    • We sat stuffily in the crowded bus during the summer heat.
    • The room was stuffily hot, so I opened all the windows.
  2. In a formal, old-fashioned, or overly serious manner.
    • He spoke stuffily about the importance of tradition.
    • She dressed stuffily in a high-collared blouse and long skirt.
    • The professor stuffily refused to accept any modern ideas.